It's All About the Bike by Robert Penn Read Free Book Online Page B

sportive-style bike: the handling will feel sharp, but the bike will be comfortable enough to sit on all day, and stable when I’m steaming down a mountain in the Dolomites at 45 mph.
    Unless you are a very experienced rider, you’ll struggle to distinguish between two sportive-style bikes with a one-degree difference in the head-tube angle, but ride a triathlon bike and then jump on a touring bike and you get the message. Be warned though; the more you learn about geometry, the faster your beard will grow.
    â€˜We’re ready to weld, Rob. You know you can’t observe TIG welding with the naked eye. It can burn your eyes out. It’s called “flash burn”. It’s like someone’s chucked broken glass in your eyes. Best avoided, so here’s a mask.’
    The TIG process entails welding tubes directly together, in a blanket of inert gas, using a tungsten welding element. The tungsten acts as a torch, heating up the tubes and the filler metal, which is fed into the weld during the process. Originally developed in the aerospace industry, it was Californian BMX frame-builders who introduced the process to the bicycle in the early 1980s. It was a grassroots innovation that went into the mainstream very quickly.
    With the mask on, I felt like Darth Vader in a village pantomime. Jason adjusted the settings on the control panel of the welder and checked the tungsten electrode. There was a great snapping sound, like a wet flag straightening in a gale, and the torch was lit. It could have been the inspiration for a light-sabre, I thought. With huge leather gloves on, and a filler rod in one hand, Jason set the torch to the tubes.
    â€˜I’m just tacking it in first,’ he said, ‘to fix the joint. Then we’ll get rid of the clamp and weld it properly.’ The jig rotated on ahorizontal axis, and Jason worked round the first joint with steady hands. When the head, seat and down tubes were welded with surgical cleanliness, he began work on the top tube: mitring, checking the tube against the frame and mitring again, over and over until he was satisfied. The front triangle was taking shape. Bare, and without stays, it looked fragile.
    â€˜It’s too easy to blow a hole through 953, the tubing is that thin and delicate. Mistakes are very expensive,’ Jason said. ‘I have to concentrate so hard, like. That’s why I won’t have people in the workshop when I’m welding. You’re a very rare exception, Rob, and that’s only because Dad bent my ear.’
    Next Jason used the jig to set the wheelbase length of the frame. ‘I’m setting the frame for a 23 mm tyre, as you agreed with Dad. The edge of your tyre will come to here,’ he said, placing a finger on the jig, a short distance behind the bottom of the seat tube, ‘but the frame will actually take any tyre from 18 to 28 mm in diameter. If you were having mudguards, or what have you, then we’d set it back here a little, but with you having pretty well a race bike, really, it’ll be here.’
    Jason set to work on the chain stays, cutting them first with a hacksaw, and then shaving them down on old Homebrew. Again, it was trial and error — shave a bit, hold it up to the frame, shave a little more . . . repeat until perfect. I was amazed at how much of the work was done by eye.
    â€˜Because no two humans are the same, no two frames are the same,’ he said, snapping the stay against the frame and the jig with a soft, metallic ‘tch-ik’. ‘I’d love to be able to pre-mitre twenty chain stays in a batch and just pop ’em in, but you can’t. Every joint has to be handmade. And that’s why it’ll only fit you right. Why it’ll be perfectly balanced, just for you.’
    The seat stays were the last tubes to be welded: they would complete the rear triangle, and the diamond shape. There areseveral ways to affix the top of the seat stays to